1. Field of the Invention
The present invention relates to an image observing apparatus arranged to enable an observer to observe a scene of the outside (outside information) and an image (display image) presented by a display device (image display means) in a single field or to an image observing apparatus intended to permit the observer to have various pseudo-experiences by superimposing an image artificially produced by a computer or the like or a picture recorded by a video system or the like on the real scene (outside information) directly observed by the observer.
2. Related Background Art
FIG. 18 is a schematic diagram to show the main part of a conventional image observing apparatus arranged to permit the observer to observe both the outside information and the display image in a single field. In FIG. 18, an image produced by computer graphics or the like is displayed on display 101, the image is reflected via a half mirror 102 by a concave mirror 103, the image is projected again via the half mirror 102 at a fixed magnification onto the eye 104 of the observer, and at the same time, the real scene of the outside world where the observer exists is superimposed through the half mirror 102 on the image to permit the observer to directly observe a superimposed image.
The apparatus of this structure has, for example, such an advantage that a worker, while carrying out an actual work, simultaneously obtains information necessary for the work through characters, a picture, etc. displayed on the display 101, and can be applied to such use.
In another application, the apparatus can also be applied to a head-mounted observing apparatus arranged to enable the observer to have various pseudo-experiences, for example, in such a manner that images of vase 106 with parallax are produced by computer graphics or the like and are displayed on respective displays for the left and right eyes of the observer whereby the observer looks as if the vase 106 exists on a desk 105 in the real space as illustrated in FIG. 19.
In the conventional observing apparatus, however, the images displayed on the displays are seen as a virtual image for the observer's eyes and, therefore, the displayed images are observed as a transparent or see-through image.
There thus arises a problem that the display images such as characters, the picture, or the like displayed on the displays become too dark to look in circumstances where the outside information is too bright, particularly, outside where the sunlight is strong. A conceivable countermeasure is to adjust the amount of the light from the outside by a filter or the like, so as to improve the visibility of the display screen. It was, however, impossible to adjust the light quantity only in the background part of the characters or the picture.
When the vase produced by computer graphics or the like is intended to be superimposed on the desk present in the real space so as to allow the observer to view the vase as if it is actually present on the desk, the vase looks see-through and thus a sight is different from that in the case where an actual vase is present. If a black image is attempted to be displayed, it will also become see-through and will not be able to be displayed.
In order to avoid this phenomenon, it is also conceivable to employ a method for converting the scene of the real world to an electric signal by a photographing apparatus such as a CCD camera or the like and synthesizing it with an imaginary image produced by computer graphics or the like. In this case, however, the quality of the scene of the real world is dependent on the resolving power of the camera and it is the present status that an image with a higher resolution than that of the images observed directly through the eyes cannot be obtained. There was, therefore, an unavoidable issue that the scene observed was different from that in the real world.